This report represents a very rare case of a gastric adenocarcinoma that was coexistent with hepatoid adenocarcinoma and neuroendocrine carcinoma. A 77-year-old man was admitted to our hospital due to a huge ulcerofungating mass identified at the proximal body of the stomach. After a pathological diagnosis of the tumor as a poorly differentiated adenocarcinoma was made, the patient underwent a total gastrectomy with lymph node dissection. Microscopically, the tumor consisted of three morphologically distinct components-tubular adenocarcinoma, hepatoid adenocarcinoma and neuroendocrine carcinoma. The hepatoid adenocarcinoma component resembled a hepatocellular carcinoma and produced alpha-fetoprotein. The neuroendocrine carcinoma component was positive for chromogranin and synaptophysin immunostains. This is an example of the diverse morphological and immunophenotypical differentiation of gastric carcinomas.